Spray gun air cap



y 4, 1966 D. D. WINEGAR 3,252,657

SPRAY GUN AIR GAP Filed May 5, 1965 INVENTOR. DON D. WINE 64R 06AM flatij arromver United States Patent 3,252,657 SPRAY GUN ARR CAP Don D.Winegar, 3255 Bean St., San Diego, Calif. Filed May 3, 1965, Ser. No.452,803 Claims. (Cl. 239-296) This application is a continuation-in-partof my pending application, Serial No. 255,841, filed February 4, 1963,now abandoned, bearing the same title.

The present invention relates to an air supply cap for a spray gun, thelatter having a nozzle, and more particularly to a cap for spray gunsfor paint or similar material.

The invention has for its objects to provide a spray gun air cap thatprovides means for obtaining a greater and more uniform concentration ofpaint on the surface to which the paint is applied; a more uniformlydistributed application, together with minimization of unwantedspraying; improved range and increased distance that paint can besprayed, thereby saving time and labor in the shifting of ladders andscaffolding; and confining the form of the pattern of the spray of paintso that the area thereof has a clearly defined perimeter, and wherebyspraying of the paint upon a surface can be maintained to an edge ormark, without material overspraying.

The air supply cap of the present invention includes a main body. Thisbody is provided with a central passage for receiving a nozzle forfluid, such as paint. This passage is axially aligned with the flow offluid emanating from the nozzle. The main body is also provided with atleast two conduit means. The outlets of these conduit means are disposeddownstreamwise of the aforementioned central passage, spreaddownstreamwise, and are disposed a substantially equal distance from theaxis of the central passage and the stream emanating from the nozzlethroughout the spreading width thereof.

Other features and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein preferred embodiments of the invention are illustrated.

In the drawing:

FIG. 1 is a perspective view of the cap.

FIG. 2 is a top plan view of the cap.

FIG. 3 is a cross-sectional view taken substantially along line 33 ofFIG. 2 and including the outlet end or nozzle of the spray gun.

FIG. 4 is a fragmentary sectional view taken along the line 4-4 of FIG.3.

FIG. 5 is a perspective view diagrammatically illustrating the formationof the air envelope around the sprayed fluid.

FIG. 6 is a diagrammatic view illustrating the relationship of thesprayed fluid and air envelope at the time they reach the surface beingsprayed.

FIG. 7 is a fragmentary perspective view of a modified form of cap.

FIG. 8 is a fragmentary view in section of another modified form of cap.

FIG. 9-is a sectional view taken along line 99 of FIG. 8.

Referring more in detail to the drawing, the air cap is shown generallyat as a main body secured to the spray head of an air gun (not shown) inthe usual manner, as by a rotatable coupling collar 22. The main body 20is provided with a central orifice 24 which is axially aligned with anozzle 26 leading from a container of the fluid, such as paint, which isto be sprayed. This orifice 24 is somewhat larger in diameter than theouter diameter of the tip of the nozzle 26, forming an annular passagearound said tip.

The main body 20 also includes a pair of lugs 28 and 30 which arereadilydisposed with respect to the axis of the nozzle 26 and orifice 24and are diametrically disposed on opposite sides of the orifice 24.Inner surfaces 32 on these lugs 28 and 30 flare outwardlydownstreamwise, and each terminates at its outer end in a floor 34. Inthe embodiment shown in FIGS. 1 to 4, inclusive, deflectors 36 extendfrom the lugs 28 and 30 downstreamwise of the floor 34. The innersurfaces 38 of these deflectors 36 may be straight, as shown, or may besubstantially arcuate in shape with the axis thereof the same as theaxis of the nozzle 26 and orifice 24.

Each of the lugs 28 and 30 is provided with a conduit 40 which extendsfrom the interior of the cap downstreamwise, and the end 44 thereofbeing in open communication with the inlets of conduit means 42 whichspread downstreamwise and are disposed substantially equally distantfrom the axis of the stream of fluid emanating from the nozzle, i.e.also from the axis of the orifice 24. In the embodiment shown in FIGS. 1to 4, each of the plurality of conduit means 42 includes a set of branchorifices comprising, preferably, a central orifice 44 and divergingorifices 46 and 48. As viewed in FIG. 4, showing one of the conduitmeans 42, orifice 46 diverges downstreamwise and to the left of orifice44, and orifice 48 diverges downstreamwise and to the right of centralorifice 44. Therefore, the inlet ends of these orifices join togetherupstreamwise from the outlets 50 thereof. Air under pressure, emanatingfrom the cap, is spread fanwise due to the divergence of the orifices44, 46 and 48.

It is desirable to provide the deflectors 36 beyond the downstream ends50. These deflectors are provided with grooves 52, 54 and 56 whichextend along the angles, respectively, of the orifices 44, and 46 and48. Such deflectors are omitted from the embodiment shown in FIG. 7.

Said grooves 52, 54 and 56 may be offset radially outwardly of therespective orifices 44, 46 and 48 which form downstream divergingextensions, as indicated best in FIGS. 1, 2 and 3. If desired, eachorifice 44, 46 and 48, and the groove extension of each, may be formedcoaxially, i.e., the grooves 52, 54 and 56 are not radially displacedwith relation to the orifices 44, 46 and 48.

Referring now to the embodiment shown in FIGS. 8 and 9, the conduitmeans is shown as a narrow fan-shaped slot 144 which spreadsdownstreamwise and is disposed substantially equidistant from the axisof the fluid emanating from the nozzle throughout the width and lengththereof.

Each of the lugs 28 and 30 is provided with an orifice 58, the inlet ofwhich communicates with the passage 50. These orifices 58 are disposedfor directing air transversely of and into the stream of fluid emanatingfrom the nozzle 26. As shown in FIG. 3, the outlet ends of theseorifices 58lie downstrearnwise of the end of the nozzle 26 andupstreamwise of the outlets 50 of the orifices 44, 46 and 48. I

The main body 20 has a floor60 that is provided with a pair of orifices62, one on each side of the axial orifice 24 and preferablyupstrearnwise of the outlet of the passage 24. This orifice 24 isdisposed intermediate the orifices 62 and the outlets of the orifices58.

Referring to FIGS. 5 and 6, column 64 represents the paint and airmixture formed by the paint and air, respectively emanating from thenozzle 26 and the orifice 24; columns 66 and 68 represent the airemanating from the orifices 62; and columns 70 and 72 represent the airemanating from the orifices 58. The mixture of paint and air formed bythe paint emanating from column 64 and the air emanating fromcolumns 66and 68, is represented by the numeral 74. This mixture is in a flattenedpattern, as shown. Air streams emanating downstream from the orifices44, 46 and 48 are indicated by columns 76 and 78, the former beingdeveloped by the conduit means in the lugs 28, while the area of airshown by column 78 is developed by the latter conduit means in the lug30. dui't means 44 spreads parallelly of the flattened stream of mixture74, whereby the air emanating therefrom spreads parallelly of the stream74 to provide the envelope 80.

It will be observed that these streams of air 76 and 78 gradually andfinally provide an envelope indicated by the numeral 80.

Also, the air envelope 80 confines all of the paint particles within thecolumn 74 to prevent any over-spray. The air spray columns 76 and 78 onopposite sides of the paint mixture 74 tend to compress the mixture tooval shape, as is indicated by the numeral 82. Some of the air of theenvelope mixes with the paint to help produce better atomization of thelatter.

The spread of the air spray columns 76 and 78 is dependent on theangular divergence of the orifices 46 and 48, together with grooveextensions 54 and 56. Due to .this spreading of the air spray, thecolumns 76 and 78 join to form the envelope 80 substantially closer tothe nozzle than if the described conduit means had been omitted. Thelength of the envelope 80 is, therefore, increased, as maintained by theinward pressure on the paint mixture 74. Also, by virtue of the presentinvention, a greater concentration of paint on the work is accomplished.The paint is more evenly distributed, and the unwanted spraying ismaterially minimized. Al so, by virtue of the present invention, therange and distance at which paint can be sprayed is increased, thusreducing the number of times that a ladder has to be moved in order todo a given job. In addition, the area of the paint is clearly confined,whereby spraying of the paint upon a surface can be maintained to anedge which is not to be sprayed, i.e., overspraying of the paint isminimized.

While the forms of embodiment herein shown and described constitutepreferred forms, it is to be understood that other forms may be adoptedwhich fall within the scope of the claims that follow.

I claim:

1. An air supply cap for a spray gun for fluid, which gun is providedwith a nozzle for fluid, said cap being provided with a main body, saidbody having:

(a) a central air-passing orifice through which said nozzle extends,said orifice being coaxial with the nozzle and the flow or fluidtherefrom;

(b) a plurality of air-passing orifices in said body disposed onopposite sides of the axis of the central passage, said orifices eachhaving an outlet disposed downstreamwise of the central orifice, thewalls of the main body forming said orifices being inclined 'toward theaxis of the central passage downstreamwise for directing air fromopposite sides against the fluid mixture emanating from the centralorifice and the nozzle to provide a flattened pattern of said emanatedfluid mixture; and

It will be observed that the con- (c) two air conduit means 'fordirecting air to form an envelope of air longitudinally about theflattened pattern of fluid mixture, one of said conduit means lyingsubstantially radially outwardly of one of said orifices and the otherof said conduit means lying substantially radially outwardly of theother of said orifices, each of said conduit means including angularlyspread orifices that extend downstream substantially parallelly of theflattened pattern and spreading to term said envelope and have outletsdisposed downstreamwise of the outlets of the orifices.

2. In a spray gun air cap having an axial orifice for a paint nozzle,

(a) a body having an air-receiving inner area opening into said orificefor mixture with paint from said nozzle to form a downstream column ofpaint mixture,

('b) said body having diametrally disposed orifices open to saidinnerarea of the body and disposed to direct air from said area toward thementioned paint mixture column to flatten the same, and

(c) conduit means radially outward of said diametrallydisposed orifices,

(d) each said means comprising a conduit open to said inner body areaand extending downstreamward, a plurality of diverging orificesextending from the downstream end of said conduit, and a grooveextending downstream fromv each of said diverging orifices and,respectively, along the lines thereof,

(e) said diverging grooves of the conduit means forming spreadingcolumns of air on opposite sides of the flattened column of paintmixture and then joining to encircle and press upon said paint mixturecolumn.

3. In a spray gun air cap according to claim 2,

(a) said body being provided with diametrically disposed extensionsbeyond the downstream ends of the diverging orifices,

(b) the mentioned grooves being formed in 'the inner opposed faces ofsaid extensions.

4. In a spray gun air cap according to claim 3, the grooves beingradially outwardly offset from the. respective orifices from which theyextend.

5. In a spray gun air cap according to claim 4, asecond pair ofdiametrally disposed orifices open to the inner area of the body andlocated inwardly toward the axial orifice of the first-mentioneddiametrally disposed orifices, said second pair of orifices beingdisposed to direct air from said inner area to intersect the air beingdirected to flatten the paint mixture.

References Cited by the Examiner UNITED STATES PATENTS 2,049,700 8/1936Gustaisson 239-296 2,070,696 2/ 1937 Tracy 239-296 2,587,993 3/ 1952Gray 239-296 M. HENSON WOOD, JR., Primary Examiner.

1. AN AIR SUPPLY CAP FOR A SPRAY GUN FOR FLUID, WHICH GUN IS PROVIDEDWITH A NOZZLE FOR FLUID, SAID CAP BEING PROVIDED WITH A MAIN BODY, SAIDBODY HAVING: (A) A CENTRAL AIR-PASSING ORIFICE THROUGH WHICH SAID NOZZLEEXTENDS, SAID ORIFICE BEING COAXIAL WITH THE NOZZLE AND THE FLOW OFFLUID THEREFROM; (B) A PLURALITY OF AIR-PASSING ORIFICES IN SAID BODYDISPOSED ON OPPOSITE SIDES OF THE AXIS OF THE CENTRAL PASSAGE, SAIDORIFICES EACH HAVING AN OUTLET DISPOSED DOWNSTREAMWISE OF THE CENTRALORIFICE, THE WALLS OF THE MAIN BODY FORMING SAID ORIFICES BEING INCLINEDTOWARD THE AXIS OF THE CENTRAL PASSAGE DOWNSTREAMWISE FOR DIRECTING AIRFROM OPPOSITE SIDES AGAINST THE FLUID MIXTURE EMANATING FROM THE CENTRALORIFICE AND THE NOZZLE TO PROVIDE A FLATTENED PATTERN OF SAID EMANATEDFLUID MIXTURE; AND (C) TWO AIR CONDUIT MEANS FOR DIRECTING AIR TO FORMAN ENVELOPE OF AIR LONGITUDINALLY ABOUT THE FLATTENED PATTERN OF FLUIDMIXTURE, ONE OF SAID CONDUIT MEANS LYING SUBSTANTIALLY RADIALLYOUTWARDLY OF ONE OF SAID ORIFICES AND THE OTHER OF SAID CONDUIT MEANSLYING SUBSTANTIALLY RADIALLY OUTWARDLY OF THE OTHER OF SAID ORIFICES,EACH OF SAID CONDUIT MEANS INCLUDING ANGULARLY SPREAD ORIFICES THATEXTEND DOWNSTREAM SUBSTANTIALLY PARALLELY OF THE FLATTENED PATTERN ANDSPREADING TO FORM SAID ENVELOPE AND HAVE OUTLETS DISPOSED DOWNSTREAMWISEOF THE OUTLETS OF THE ORIFICES.